This study will continue research begun under "Smoking Prevention Training for Youth." The cancer problem for the continuation study is tobacco use. The cancer control hypothesis is that complementary knowledge and skills will help above-average risk youth avoid tobacco use. Prevention in defined populations is the cancer control intervention. The Phase 4 study will: Evaluate methods to prevent tobacco use with persons from rural, blue-collar, low-income, nonwhite, or single-parent backgrounds; Evaluate booster sessions to maintain tobacco use prevention effects; Validate an index to assess future tobacco use; and Measure test reactivity in tobacco use prevention research. Two panels of sixth-grade students will be screened for future tobacco use risk. Youths with above-average scores will be defined as high risk. Forty-eight schools with enrollments of at least 50% high-risk students will be divided into four conditions. Two experimental conditions will receive 18 sessions on informational, problem solving, self-instructional, communication skills, and media analysis methods to prevent smoking. One experimental condition will receive semiannual booster sessions when subjects are in seventh, eighth, and ninth grade. The independent variable will be monitored with observational data, subject feedback, and session summaries. Two conditions will be untrained controls. One condition will be tested only at the beginning and end of the study. The other control condition and both experimental conditions will be tested annually. Outcome measures will cover demographic information, biochemical samples and self-reports of tobacco use, self-reported health behavior, locus of control, self reinforcement, problem solving, interpersonal coping, assertiveness, social networks, and self-efficacy. Follow-up batteries will measure contagion relative to prevention curricula. Results will be analyzed for the effects of gender, demographic characteristics, prevention curriculum, and booster sessions. Multivariate procedures will prospectively test an index to predict youths' future tobacco use and nonuse.